Python techniques for student PDF

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Python Technique note for information and technology student...

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Python techniques - Input two number or more on the same line.  Map(function,interable) can apply a function onto interables, so we use split() to change inpu in to list so that map can work on them , and apply int function . - N digits after decimal point and the use of format() function.  Format function can place value inside a placeholder ( {} )  {:.2f} is used to define a value and specifies the decimal point ( change the number to change decimal point ) - Int object is not iterable

 For ex: we want to do sth in a number ( 123443234 ) we can’t work on each digit in this number if it is an int , so we can change it to str to process and change it again to int to operate on them. - The divide operators in python is very tricky so you need to understand them: + The % will divide and take the rest as the answer ( 5 % 2 = 1 ) + The // will give the result down to the nearest whole number (15//2 =7) + The / will give the result if it is fully divideable if itn’t it will return float = 4 but 13 / 3 = 4.33333)  Using these operator flexibly and you can work with number much easier for ex : + 2134 % 10 = 4 ( so you can take the last digit of a number ) + 2134 // 10 = 2134 ( so you can eliminate the last digit of a number )

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- We usually use for loop when we are certain of the number of input or if there is only one input  In this example we want to calculate the sum of a number and all the number before it ( 5 = 15 )  We are certain of the input and the number of it so we can use for loop  Note that range will only run from ( begin to end – 1)  So in this case we declare range (1 , x +1 ) - We usually use while loop when we arent certain of the numbe of input or if we need to input limitless or too many input.

 In this ex we want to input limitless input until input is 0 so we use while loop .  There should be a condition for break or else the loop will be endless.

- When we want to compare two input or more we can use this technique .  In this ex: we want to compare each input x with max and min, so we declare two var (max min) as a holder for x.  In the very first input ( for ex 1 ) max and min will be reset to 1 ( 1 >0 => max = 1 ) ( 1 min = 1 )  And in the next input x will be compare with 1 to find which will be max and min and so on.

- Setting Flag is an useful technique to process through all input before printing out output or when we want to delay printing out output for some reasons.  In this code to find prime number, line 4,5’s flag is used to dela printing out output ( as it’s only the first case and we need to work on orther cases also ).  From line 6 -> 7, this flag is used to process through all of our input ( if we don’t use flag here and say print(“NO”) it will print no or yes each time x is divided by i and that’s not what we want).

 We can set flag to true or false base on the problem for ex: + Input a list of number, is it true that all of this number is fully dividable by 3 ? case we can set flag = true and find 1 number that is not then break. + Input a list of number, find at least 1 number that is dividable by 5 ? case we can set flag = false and find 1 number that is dividable then break.

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- Remember that when declaring a function the position of return is very important.  If we want to return count after processing all the output remember to place return outside of the loop.  In fact pay close attention to the position of return in all cases.

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